The present invention relates to flight safety, and in particular to a flight safety system that monitors sets of state values to provide warnings of potentially unsafe situations.
Controlled Flight Into Terrain (CFIT) accidents have received much attention recently, but most attempts to address them have concentrated on making flight crews more aware of terrain. However, a study of recent accidents suggests that many are caused by factors unrelated to terrain. Many such accidents are near airports, where conventional terrain avoidance/warning systems are ineffective due to the inherent lower altitude of the plane required for landing. Such conventional systems usually rely upon a measurement of one parameter.
In one example, a wrong descent mode is thought to have been selected. While the crew selected a parameter for a flight path angle, it was applied to a vertical speed mode of descent. The parameter was too great for such a mode, likely causing the accident. In a further example, it was not realized that a first officer""s flight director was still selected and the autoflight system was following Flight Director guidance. In one more example, a crew failed to retract speedbrakes when attempting to climb out of a canyon.
An aircraft signal definition is provided to enable definition and monitoring of sets of aircraft input signals to customize such signals for different aircraft. The input signals are compared against known combinations of potentially dangerous input signal values by operational software and hardware of a monitoring function. The aircraft signal definition is created using a text editor or custom application.
A compiler receives the aircraft signal definition to generate a binary file that comprises the definition of all the input signals used by the monitoring function. The binary file also contains logic that specifies how the inputs are to be interpreted. The file is then loaded into the monitoring function, where it is validated and used to continuously monitor the condition of the aircraft.
Undesirable input value combinations describing the state of an aircraft are initially identified by experts. Error messages and identification of potential alarms are generated based on both knowledge of actual accidents, and on use of expert knowledge to predict potentially dangerous states. The combinations are entered into the aircraft signal definition for use by the monitoring function. Different aircraft signal definitions are written for different aircraft, and are useable with identical monitoring functions.